To date, no other exporters have followed suit. A full blockage of the strategic waterway would virtually halt shipment to Europe and the United States of about 4.8 million barrels per day of crude oil and refined petroleum products

Rouhani's apparent threat earlier this month to disrupt oil shipments from neighbouring countries came in reaction to looming U.S. sanctions and efforts by Washington to force all countries to stop buying Iranian oil

According to the list, the Hinduja brothers - Srichand and Gopi in London, Prakash in Geneva and Ashok in Mumbai - have seen sharp increases in profitability in Ashok Leyland, InduSind bank, Gulf Oil, energy and real estate.